1. Field of the Invention
The present invention relates to a manufacturing process of tea in which any muddiness or precipitate does not occur during storage for a long time. The tea has excellent flavor and is suitable especially as a transparent container type product.
2. Description of the Prior Art
Sometimes the muddiness and precipitate occur during storage of the produced tea beverages, particularly the green tea beverages, for a long time. The solution of this phenomenon has been an important point in manufacturing process for a transparent container type of tea beverage. It is considered that this phenomenon is due to precipitate formed by the binding of metal ions extracted from tea leaves and protein, pectin, polyphenol or the like also extracted from the leaves. Therefore, for the prevention of precipitation in the tea beverages, it has been important to remove the metal ions extracted from tea leaves.
As one of conventional measures against this phenomenon, a removal method of the metal ions is described in Japanese Laid-Open Patent Publication No. 154462/1975. In this method, an enzyme mixture containing tannase, cellulase, hemicellulase, xylanase, pectinase or the like is added to the tea extract for solution of a precipitate like cream, then this extract is treated with cation exchange resin for removal of metal ions such as calcium, aluminum, magnesium, manganese, iron and the like contained therein.
This method has been worth notice, in that the metal ions are effectively removed, and a large-scale equipment is not necessary. However, there has been a problem in this method that the natural flavor of tea is changed and spoilt.